Symmetry of the lowest conduction band states in very short-period GaAsAlAs superlattices

Abstract

The symmetry of the lowest conduction band minimum (CBM) in type-II (GaAs) n (AlAs) n short-period superlattices (SL) was investigated by photoluminescence (PL) decay, PL excitation (PLE) and PL under uniaxial compressive stress. The results show that for n ⩾ 4, the CBM is in the center of the SL Brillouin zone (BZ) and the wave function is mainly derived from the bulk X z state. For n ⩽ 3, the CBM is away from the center of the SL BZ, and derives mainly from the bulk X x, y states. Interface disorder plays an essential role in both the transition probabilities and the energy levels.